Sirius was waiting outside the door at number 12, grimauld place. He saw harry struggling with Remus and ran over to help someone, though he didn't know who.

"Sirius, come help, harry doesn't want to be here for the full moon!" Remus said somewhat hurriedly. Sirius immediately understood. He didn't help Remus, but he knelt down and talked to harry.

"Harry, werewolves don't attack other animals" He said.

"But Lupin attacked you last time he transformed!" Harry said, still struggling.

"Yes, but that was because I was barking at him. Plus you have drank the wolfsbane potion, and remus hadn't." Sirius said back. Harry stopped struggling and allowed them to lead him into the house. And not a moment too soon, for just a few seconds later the moon shone on Harry and Remus's faces from a nearby window while Sirius was locking and securing the door. Slowly harry started to transform and so did remus.